Mechanisms of disease in patients with chronic stable angina

Background: The concept of multiple mechanisms underlying chronic ischemic heart disease (IHD) has been included in recently published major guidelines. Nonetheless, “alternative” mechanisms are called into question only when obstructive coronary artery disease (CAD) is excluded. Similarly, positive stress test results of patients with no obstructive CAD are frequently regarded as inacurate. This study sought to assess consistency of response among different stressors in patients with suspected chronic stable angina and to investigate the impact of coronary anatomy on stress test results. Methods: Patients with suspected angina and no known CAD or exclusion criteria underwent stress echocardiography with exercise, dobutamine and dipyridamole. Patients with at least one positive result underwent coronary angiography and those with significant CAD underwent complete revascularization, as appropriate. At 6 months from index revascularization patients repeated the test(s) resulted positive at initial evaluation. Results: Fifty-seven patients qualified and were included in the study (mean age 63 years; 77% males). The majority (58%) displayed inconsistent results among different stressors. At univariate analysis CAD did not significantly affect stress test results. Twenty nine patients underwent successful and complete revascularization. At 6 months from revascularization, 27% displayed persistent positive stress test result. Conclusions: When multiple stressors are used for ischemia precipitation there is a low agreement between stress test results, a finding that supports the theory of multiple mechanisms underlying myocardial ischemia. Coronary anatomy does not significantly affect stress test results, thus suggesting that “alternative” mechanisms should be irrespectively explored.